1. Field of the Invention
The present invention relates to a method of manufacturing a solar cell, and more particularly to a method of manufacturing a solar cell including a selective emitter.
2. Description of the Related Art
Recently, research into new renewable energy sources that can reduce environmental pollution has been actively conducted as problems in terms of environmental pollution are aggravated. Among these new renewable energy sources, in particular, solar cells, which produce electrical energy from sunlight, are receiving attention.
A solar cell, which is a photoelectric conversion element that directly converts sunlight into electrical energy, has a junction structure of p and n type semiconductors and a basic structure thereof is similar to that of a diode. Solar cells are classified into silicon solar cells and compound semiconductor solar cells according to their manufacturing materials and are classified into a substrate type and a thin-film type according to shapes thereof. Currently, a substrate-type crystalline silicon solar cell is widely used for solar power generation and includes a silicon substrate, an n-type layer that is disposed on a front surface of the silicon substrate and acts as an emitter, a p-type layer disposed on a rear surface of the silicon substrate, and a reflection preventing layer such as a silicon nitride film, an oxide film, or the like to minimize reflection of light.
Solar cells that are currently used mostly for industrial applications are manufactured using a screen-printing method and have a photoelectric conversion efficiency of approximately 15-18%. However, it is difficult to anticipate higher efficiency using currently used structures and manufacturing processes, and thus, development of a variety of structures and manufacturing processes is underway worldwide.
A selective emitter structure is one technique used to manufacture high-efficiency solar cells, and is configured such that only an electrode part of a solar cell is locally doped at a high concentration and the remaining part thereof (a part to absorb light) is doped at a low concentration, which gives the selective emitter structure advantages of both a high-concentration emitter layer and a low-concentration emitter layer.
To form a selective emitter, techniques such as laser scribing used for buried contact solar cells (BCSCs), photolithography used for passivated emitter rear locally (PERL) diffused cells, and the like have been developed. However, most of these techniques require a high-temperature process in two or more steps and thus manufacturing costs increase and production yield decreases.
Therefore, there is urgent need for high-efficiency crystalline silicon solar cells that do not require complicated manufacturing processes and can be mass-produced.